I am a glass art student so I sometimes come across these things the temperature would have to get very high for a set window to change shape. I mean somewhere over 900 degrees because this is the temperature at which we put our glass away.

Glass is pretty much forever, it is an incredible substance unlike anything else. Also I have been wondering about how to properly store discs. They are upright in the store so I am guessing this is the best way. Gravity is still a great force, though.